News

In Tillamook: Turning (More) Cow Poop Into Power

A lactating dairy cow can produce more than 100 pounds of manure a day. Handling that manure properly is a major expense for dairy farmers, and can result in air and water pollution. Methane digesters that turn the poop into power can also help improve dairy air and water quality.

A company called Farm Power Northwest is building two new methane digesters in Tillamook that will turn dairy cow poop into power. One will start up next month, taking manure from cows on five dairies and turning it into 1 megawatt of electricity – enough to power about 700 homes for a year. The second, yet to be built, will use the manure from one farm to produce 750 kilowatts of electricity –enough to power about 500 homes a year.*

Methane digesters are not new. The Port of Tillamook Bay has been operating a community digester since 2003. But the technology is getting more efficient, and it’s sprouting up in more and more locations around the Northwest as farmers and power producers realize it offers many other benefits in addition to renewable energy.

On top of Farm Power Tillamook's methane digester, the methane gas is collected in a pipe and burned in a generator to create electricity.

The digesters essentially cook the methane out of cow manure and then burn the gas to generate electricity.

Manure from nearby farms is piped into a receiving pit at Farm Power Tillamook, where it will be fed into a digester where bacteria will eat the sugars and proteins and produce methane gas.

Digesters are usually too expensive for small farms to install on their own. So Farm Power Northwest is making a business out of pooling the poop from several small farms to feed one mid-sized digester.

Here’s how it works: The company will pay Tillamook farmers around $60 a year per cow for their manure. The manure is piped into a receiving pit and fed into the digester, which acts like a cow’s stomach to warm up bacteria in the manure to about 100 degrees.

The bacteria eat the remaining sugars and proteins in the manure and produce methane gas. The gas is captured in a pipe above the digester and fed into a generator, where it is burned to make electricity.

“It’s like our own little natural gas well except we’re not taking it out of the ground,” said Daryl Maas, a co-founder of Farm Power Northwest. “We’re harvesting it from manure.”

Water pipes running through the generator capture the waste heat from the process and send it back into the digester to warm up the incoming manure.

The power will be sold to the Tillamook People’s Utility District, and the carbon offset credits from the reduced methane emissions will be sold to Puget Sound Energy or Climate Trust.

“It’s like our own little natural gas well except we’re not taking it out of the ground. We’re harvesting it from manure.” — Daryl Maas, a co-founder of Farm Power Northwest

The process kills the stinky and polluting bacteria in the manure. So, the water leftover can be piped back to the farmers and used as a cleaner fertilizer than they had before. And the leftover solids from the manure can be separated to create much cheaper cow bedding material than the wood shavings farmers have traditionally used (which are getting more expensive because wood waste has market value for power production, too).

The digester arrangement works out well for the farmers and the power producers, said company co-founder Daryl Maas, who grew up in the dairy farming community in Mt. Vernon, Wash.

“Our goal was to make it no impact for the farmer. They usually store the manure in a tank and use it as fertilizer,” he said. “We want the methane, and they want the phosphorous and nitrogen.”

Most dairy farmers store their cow manure in a tank and spread it on their pastures as fertilizer, but that can create air and water pollution. Methane digesters kill pathogens in manure and reduce odor and water pollutants.

Chad Martin of Martin Dairy said he had been looking into installing his own digester before Farm Power Tillamook proposed to build one near his property. He agreed to send manure from his 900 cows to the Farm Power project because he would get cleaner fertilizer without additional costs.

He already separates and composts the fiber from his cows’ manure to make cow bedding, but the liquid manure he sprays on his grazing pastures is smelly and has to be handled carefully because it can pollute nearby waterways.

“Manure is so expensive to handle,” he said. “You’re kind of limited in what you can do out here because it’s so wet.”

The business model for starting a new methane digester is a little risky. As this article in Sustainable Business Oregon reported, they cost $3 million to $4 million to build and last about 30 years. But if the dairies feeding them facing go under they can lose their feedstock, and the about half the $500,000 in annual earnings from power sales goes back into maintaining operations.

Farm Power’s digester start-ups have relied on help from the U.S. Department of Agriculture to get off the ground. Farm Power Tillamook tapped a $2.65 million loan guarantee and a $100,000 grant from the USDA’s Rural Development Program. But that was enough to allow the company to secure private financing for the rest of $4 million digester.

Burning methane to generate electricity does release air pollutants, but it reduces more greenhouse gases than it produces. That allows the owners to make extra money from carbon offset credits.

Jill Rees of the U.S. Department of Agriculture’s Rural Development Program in Oregon said her agency supports digester projects – “just enough to get good projects over the hump.”

The reason is primarily economic development but also to develop a new source of renewable energy, she said. The projects have the added benefits of preventing greenhouse gas emissions and improving air and water quality as well as dairy farm operations.

“In a lot of these cases farmers are interested in the technology but they already have a job to do,” she said. “They’re interested in seeing how can this benefit them, and they’re supportive but they don’t have the ability to do it themselves.”

A report released last year by The Climate Trust and The Energy Trust of Oregon assessed the potential for more biogas, which can come from manure, sewage, garbage, plant and food waste.

It concluded the state’s biogas industry could grow to 12 times its current size and generate 100 megawatts of power. Dairies offer the largest biogas opportunity, the report found, with 140,000 cows on 150 farms offering 46 megawatts of potential energy.

The report said biogas could cut 800,000 metric tons of carbon-dioxide equivalent emissions in Oregon – almost 5 percent of the reductions the state needs to meet its 2020 greenhouse gas goals.

But building the biogas facilities – such as a methane digester – costs money. And tapping their environmental benefits might require additional incentives from state government such as tax credits or requirements for utilities to buy a certain percentage of biogas.

Maas said his company is essentially competing with natural gas, which has been getting cheaper and cheaper as hydraulic fracturing technology unlocks new supplies from shale rock. Low natural gas prices make it harder for new methane digester projects to pencil out.

“We’re fundamentally still a power producer. We compete in a power market,” he said. “Right now the power price we can get for new facilities is falling because of gas prices. Like everything else with renewable energy, it has to compete with fossil fuels.”